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1 /* SPDX-License-Identifier: 0BSD */
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2
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3 /**
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4 * \file lzma/hardware.h
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5 * \brief Hardware information
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6 * \note Never include this file directly. Use <lzma.h> instead.
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7 *
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8 * Since liblzma can consume a lot of system resources, it also provides
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9 * ways to limit the resource usage. Applications linking against liblzma
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10 * need to do the actual decisions how much resources to let liblzma to use.
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11 * To ease making these decisions, liblzma provides functions to find out
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12 * the relevant capabilities of the underlying hardware. Currently there
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13 * is only a function to find out the amount of RAM, but in the future there
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14 * will be also a function to detect how many concurrent threads the system
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15 * can run.
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16 *
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17 * \note On some operating systems, these function may temporarily
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18 * load a shared library or open file descriptor(s) to find out
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19 * the requested hardware information. Unless the application
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20 * assumes that specific file descriptors are not touched by
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21 * other threads, this should have no effect on thread safety.
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22 * Possible operations involving file descriptors will restart
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23 * the syscalls if they return EINTR.
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24 */
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25
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26 /*
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27 * Author: Lasse Collin
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28 */
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29
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30 #ifndef LZMA_H_INTERNAL
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31 # error Never include this file directly. Use <lzma.h> instead.
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32 #endif
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33
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34
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35 /**
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36 * \brief Get the total amount of physical memory (RAM) in bytes
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37 *
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38 * This function may be useful when determining a reasonable memory
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39 * usage limit for decompressing or how much memory it is OK to use
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40 * for compressing.
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41 *
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42 * \return On success, the total amount of physical memory in bytes
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43 * is returned. If the amount of RAM cannot be determined,
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44 * zero is returned. This can happen if an error occurs
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45 * or if there is no code in liblzma to detect the amount
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46 * of RAM on the specific operating system.
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47 */
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48 extern LZMA_API(uint64_t) lzma_physmem(void) lzma_nothrow;
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49
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50
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51 /**
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52 * \brief Get the number of processor cores or threads
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53 *
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54 * This function may be useful when determining how many threads to use.
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55 * If the hardware supports more than one thread per CPU core, the number
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56 * of hardware threads is returned if that information is available.
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57 *
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58 * \return On success, the number of available CPU threads or cores is
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59 * returned. If this information isn't available or an error
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60 * occurs, zero is returned.
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61 */
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62 extern LZMA_API(uint32_t) lzma_cputhreads(void) lzma_nothrow;
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